Plaster base and wall formed therewith



Feb. 29, 1944. H. R. HAY

PLASTER BASE AND WALL FORMED THEREWITH Filed Jan. 19, 1940 Patented Feb. 29, 1944 PLASTER `BASE AND WALL FORMED THEREWITH Harold R. Hay, New Orleans, La., assignor to The Celotex Corporation, Chicago, Ill., a corporation of Delaware Application January 19, 1940, Serial No. 314,574

(Cl. i2-124) 7 Claims.

This invention relates particularly to an improvement in plaster base units and to an improved plaster wall structure incorporating suchunits as the plaster base receiving members thereof, and particularly the invention relates to the provision of such a construction wherein the tendency of the applied plaster to crack over the joints between adjacent plaster base units is very greatly reduced if not entirely eliminated.

The invention hereof will be hereafter described in` connection with the accompanying drawing wherein in the various figures thereof like reference numerals are used to designate like parts therein.

In the drawing Fig. 1 is an elevation of a portion of a `wall surface composed of a plurality of the improved plaster base units illustrating a preferred construction and a modification thereof;

Fig. 2 is a section taken on Figure 1 along the line 2 2 thereof illustrating the preferred construction, looking in the direction of the arrows; and

Fig. 3 is a section taken on Figure 1 along the line 3-3 thereof illustrating the modification, looking in the direction of the arrows.

In heretofore known constructions there has been provided, as the plaster base, a fibrous insulating board applied in relatively small units, the edges of these units shiplapped and beveled as illustrated in the accompanying drawing, this type of unit being disclosed in greater detail yin the patent to Treadway B. Munroe #1,841,757 dated January 19, 1932, but in such patented and herefore known plaster base unit construction there is some tendency, at least under certain conditions, for the applied plaster as a sheet to crack along the horizontal joints between successive rows or tiers of such units in thel erected and finished wall.

It is particularly an object of this invention to improve upon the construction of the fibre board plasterA base unit disclosed in sail patent above referred to, and in connection therewith it is the further object of this invention to provide on such units auxiliary channels or recesses adapted to receive additional plaster sheet reinforcements, whereby the object of the invention is achieved, namely the decrease in the tendency of an applied plaster sheet to crack along the horizontal joints.

To this end, and with particular reference to the accompanying drawing, there is illustrated a plaster base unit IIJ, which is of rectangular shape and preferably of the usual commercial dimensions of 16" x 48" whereby a plurality of such units may be conveniently and expeditiously applied to studding II or the like irrespective of whether the studding is spaced on 16" centers or on l2 or 24" centers. These units I0 are preferably formed of fibre insulating wallboard and are preferably 1/2 in thickness although, of course, it will be understood that if these units are of greater thickness, say 3A" or l", they will be correspondingly and inherently stiffer, and therefore they will form a stronger and more solid plaster receiving base.

These units I0, as illustrated in the drawing, are provided along their edges with complemental bevel and shiplap joint construction, vthe bevels indicated by the numeral I2 being on the plaster receiving side of the unit, and the shiplap formation indicated by the numeral I3 being on the opposite or rear side thereof. The bevels are provided on all four edges of the unit, are of substantially 45 inclination, and extend substantially half way through the thickness of the unit wherefore, when a plurality of these units are assembled into the wall structure as shown in Fig. l, a bevel of one unit will meet a bevel of the next adjacent unit, and thus there will be provided a V-shaped groove I4 surrounding each unit in the wall structure.

The units are secured to the studding so that the length of each unit is in a direction extending across a plurality cf the studs II, as shown, whereby the shiplap formation between adjoining tiers of the units tends to strengthen the unsupported lhorizontal joint between two adjacent studs; the vertical joints between units ina tier are positioned upon a stud. Hence, when plaster is applied over the face of the units in the wall structure, the plaster will not only adhere to the planar surface of the units in the wall by virtue of the keying effect afforded by the fibrous character of the units, but the plaster will fill the V-shaped grooves I4 thereby forming reinforcing ribs in the plaster, such ribs tending to overcome and materially lessening the cracking of the plaster, particularly in a direction transverse to the horizontal joints between the plaster base units I0.

It is of course to be understood that alternatively to the bevel and shiplap joint construction, particularly disclosed in the accompanying drawing, there may be substituted therefor any equivalent joint construction which will serve to receive a plaster sheet reinforcing rib or ridge over the joint between adjoining units I0 and providing a construction wherein the joint between such units is relatively closed and is not of an open or direct character in the wall structure. An example of such alternative joint construction is one wherein the edge portions of a unit are bevelled but the extreme joint forming edges are formed with interfltting complementa] tongues` and grooves in the nature of tenons and mortises.

As above indicated, the unsupported edges of further, and practically eliminate such, crack formation.

To this end, V-shaped grooves such as I are additionally formed at spaced intervals in the unit IIJ extending inwardly of the unit from,

and substantially at right angles to, the edge bevel, such groove serving as an auxiliary to the V-shaped groove I4 between two adjacent units. Where the unit is substantially 16 x 48" in size, and the studs II are on 16" centers, these auxiliary grooves are substantially 4" in length, the bottom of such grooves sloping or tapering into the surface of the unit from a depth at the edge of the unit substantially equal to the depth of the bevel I2, as clearly indicated in Fig. 2, the width of the auxiliary groove at the bevel being substantially equal to the width of the main groove Il. Further, these auxiliary grooves, I5 are spaced in the unit so as to be located between the studs II or other beams, and when the studs are on 12 or 16" centers a single auxiliary groove, disposed substantially midway between the studs as indicated in Fig. 1, has been found sufllcient; one or more such grooves, however, may be provided in accordance with the thickness of the plaster base unit and/or the sheet of plaster thereon, as well as in accordance with a greater separation between the studs as for example when the studs are on 24" centers, and the length of a groove may be varied from the 4 dimension above mentioned likewise in accordance with such conditions.

The auxiliary grooves need not be of V-shape, since grooves of different shapes will accomplish the desired result of forming an additional auxiliary reinforcing rib in the plaster sheet and extending laterally from the primary reinforcing rib in the regionof the main groove Il. A different shaped auxiliary groove is indicated at I6 in the drawing and comprising a semi-circular recess of maximum depth at the bevel I2 and decreasing or tapering in its depth toward its circular periphery; such groove or recess I 6 may be of the same lateral extent, from the bevelled edge of the unit, as the V-shaped auxiliary groove I5 but, due to the increased total area of the circular groove I6, it may be of a shorter lateral extent and yet give the necessary reinforcement to the plaster sheet to prevent the hereinabove mentioned formation of cracks. Also, one or more such circular recesses may be provided in the region between adjacent studs, as previously mentioned in connection with the grooves I5.

When the units I0 .are assembled into the wall structure, the auxiliary grooves of one unit will register with those of the unit in the next adjacent tier of units due to the spacing of such grooves and as clearly shown in Fig. 1, and thereby make possible a very strong reinforcement of the plaster sheet at points intermediate the studs I I. In other words, the otherwise continuous extent of the primary reinforcing plaster rib, formed at the horizontal joint between the tiers of units I0, is divided into short sections by the auxiliary ribs, formed by the auxiliary grooves such as I5 or I6, so as to reduce and substantially nullify the tendency for a crack to start over a horizontal joint between units and possibly to travel entirely across the side of the room (wall). Cracking, when it does occur, is generally over the line of merger of a bevel I2 into the face of a unit I0, this being the weakest point since that portion ofthe plaster sheet directly over the unit joint is reinforced by the primary rib of Vplaster lying in the main groove formed by the adjacent bevels I2. By providing the auxiliary ribs of plaster within the auxiliary grooves I5 or I6, this weakest point or point of maximum stress in the plaster sheet is reinforced and the stresses are distributed in such sheet to regions further back from the unit joint, and hence the cracking is minimized if not actually prevented under normal conditions.

From the foregoing description it will thereforebe seen that by this invention there is provided a wallboard of yielding fibrous cellular character, said wallboard provided with a face adapted to receive a coat of plastic material such as plaster, there being formed a bevel meeting said face and adjacent an edge of the wallboard, said bevel also adapted to receive plaster, and a. plaster receiving recess in said face, said recess extending inward from said bevel and tapering into said face, the greatest depth of said recess being substantially in the line of said bevel. More specifically the recess may be of various shapes such as a V-shaped groove, or it may be substantially semi-circular in shape with its diameter lying substantially in the line of said bevel. Further, this invention contemplates a wall structure comprising supports and wallboards supported thereby said wallboards of the character described, the supports being substantially parallel to each other, the wallboards set edgeto edge on the supports and similarly formed and complementally associated in the wall structure with the edge bevel of one board meeting the edge bevel of the next adjacent board to provide a primary groove in the wall structure, and the recess of one board in registration with the recess of the next adjacent board to provide together an auxiliary groove intersecting such primary groove, and a plastic sheet (plaster) applied to the faces of the boards and having on its rear side reinforicng ribs extending into the primary and auxiliary grooves of the boards, the auxiliary groove disposed intermediate two adjacent supports in the wall structure.

It is obvious that those skilled in the art may vary the details of construction and arrangements of parts without departing from the spirit of this invention and therefore it is desired not to be limited to the exact foregoing ldisclosure except as may be required by the claims.

` What is claimed is:

1. A wallboard provided with a face, a bevel meeting said face adjacent an edge of the wallboard, and a recess in said face transversely formed with respect to the bevel', said recess comprising a V-shaped groove extending inward from said bevel and tapering into said face.

2. A wallboard provided with a face, a bevel meeting said face adjacent an edge of the wallboard, and a recess in said face, said recess being substantially semi-circular in shape and extending inward from said bevel and tapering into said face.

3. A wallboard provided with a face, a bevel meeting said face adjacent an edge of the wallboard, and a recess in said face, said recess being substantially semi-circular in shape and extending inward from said bevel and tapering into said face, said recess having its diameter lying substantially in the line of said bevel.

4. A wall structure comprising supports and fibrous yielding board-form plastic-receiving base units supported by the supports, opposite edges of each unit provided with a bevel meeting the plastic-receiving face of the unit, each unit having a recess in such face intermediate opposite edges of the unit and along an edge thereof and extending inwardly from such bevel and tapering into such face, the units similarly formed and complementally associated in the wall structure with the edge bevel of one unit meeting the edge bevel of the next adjacent unit to provide a primary groove in the wall structure, and a recess Iof one unit in registration with the recess of the next adjacent unit to provide together an auxiliary groove intersecting such primary groove, the recesses thereof extending inwardly from their respective bevels and tapering into their respective faces in the direction of the recesses and bevels, and a plastic sheet applied to the faces of the units and having on its rear side reinforcing ribs extending into the primary and auxiliary grooves on the face of the base.

5. A wall comprising a plurality of similarly fstantially in formed and yieldable fibrous boards set edge to edge, adjacent edges of the boards being bevelled to form a substantially V-shaped primary groove adapted to receive plaster, each board having a plaster-receiving recess in its face transversely formed with respectgto the bevel and extending inward from a bevelled edge and tapering into such face in the direction of the recess and the bevel, the transverse recess of a board in registration with the transverse recess of the next adjacent board, such registering transyerse recesses together forming an auxiliary transverse groove intersecting the primary groove, and a sheet of plaster applied to said boards and lling all of said grooves, the plaster in said grooves constituting ribs reinforcing the plaster sheet.

6. A wallboard provided with a face, a bevel meeting said face adjacent an edge of the wallboard and a recess in said face, said recess extending' inwardly from the beveled edge of the wallboard andthe said recess tapering from its deepest portion in all directions toward the face of the wallboard.

'7. A. wallboard of yielding fibrous character, said wallboard provided with a face and adapted to receive a coat of plast-er on such face, a bevel meeting said face adjacent an edge of the wallboard, saidr bevel also adapted to receive plaster thereon and a plaster receiving recess in said face intermediate opposite edges of the wallboard and along an edge thereof and said recess transversely formed with respect to the bevel and extending inwardly from said bevel and tapering into said face, the greatest depth of the recess being subthe line of the bevel and thence tapering in al1 directions to the face of the wallboard.

HAROLD R. HAY. 

